White non-staining portland cement and process of making same.



' pure, white and non-staining Portland ce-' UNITED STATES PATENT OFFICE.

SPENCER B. NEWBERRY, or SANDUSKY, 01110.

WHITE NON-STAINING PORTLAND CEMENT AND PROCESS OF. MAKING SAME.

bio-900,874.

suitable for casts and ornamental artificial stone-work, and also, owing to its non-staining qualities, especially adapted for use mortar for laying up marble, standstone, limestone brick or terra-cotta walls or facings of buildings, for. which purpose ordinary Portland or natural hydraulic cements can not advantageously be used, owing to their tendency to stain the stone. The gray or brownish color and staining qualities of ordinary Portland or natural cement vare caused by impurities, consisting chiefly of compounds of iron, contained in the mate-' rials from Wl 11Cll these cements are made.

My experiments have shown that it is possible to make a Portland cement of the highest hardening qualitiesfrom materials free from iron and consisting of lime, silica and alumina only.

In order to obtain in a commercial way a ment, it is necessary that the mixed. materials shall contain not more than two tenths of one per. cent, or at most three tenths of one per cent., of iron oxid. And in order to produce a slow setting cement of good herdened qualities, it is necessary, also, that the clay employed shall be silicious containing preferably from two and one half to three and one half times as much silica as alumina. It is not possible to use the ordinary white Specification of Letters Patent. Application filed March 13, 1905. Serial No. 249,787.

Patented Oct. 18, 1908.

' clays or kaolins, which contain much more' alumina than the above proportion.

In making a white non-staining Portland cement, pure limestone and silicious clay,

substantially as above defined, practically free from iron, is mixed in the proper proportions, andto the mixture is added cryolite (the doublefluorid of aluminum and sodium). The cryolite is thoroughly mixed with the raw materials before burning, and from two to five per cent. of the cryolite is employed. 1 find that when this mixture'is subjected to heat, the cryolite takes the place of-the iron oxid, in'ordinary cement mixtures, and acts similarly thereto in promoting the combinationof the ingredients and the sintering of the clinker produced, and that such cryolite does not import into the cement any staining ingredients, and does not injure the hydraulic qualities of the resulting cement.

Claims:

1. The herein described process of producing a white non-staining Portland cement, which consists in mixing together white limestone, 'silicious clay as herein .defined,

and a small percentage of cryolite,said

mixture being substantially free from iron,- and burning the resulting mixture in the usual way, substantially as specified.

2. As a new article of manufacture, a white, non-staining Portland cement formed by burning a mixture of White'limeston, si-

licious clay as herein defined, and a small percentage of cryolite,--said mixture being substantially free from ir'on, substantially as specified.

In testimony whereof, I hereunto aflix my signature in the presence of two Witnesses. SPENGER B. NEWBERRY.

Witnesses.

HENRY J EAvoUs, BERT MARTIN. 

